In order to better understand the background of the present invention, a description will be given of the eye in conjunction with the FIG. 1. With reference to FIG. 1, there is shown the anatomy of the eye in a cross-sectional view. In the eye, incident light beams are refracted mainly in a cornea 1 and lens 5 so as to form a focus on a retina 9, as in a camera. This allows a human to visualize or see an image or a scene from the retina 9 as transmitted by the optic nerve 8. When becoming turbid for congenital or acquired reasons, the lens 5 cannot refract external light beams appropriately to form a focused image on the retina 9. Serious turbidity of the lens 5 may result in the loss of one's sight.
As shown in FIG. 1, an anterior chamber 2 is formed behind the forward portion of the cornea 1 and ahead of the iris plane 3 and forward of the forward surface 4 of the crystalline lens 5. Sclera 7 extends outwardly from the cornea 1 along the eye. Vitreous body 6 will reside behind the lens 5 and forward of the retina 9. The vitreous body will fill the interior of the eyeball. A posterior chamber 10 is positioned rearwardly of the anterior chamber 2 so as to communicate the fluid flow of aqueous humor between the posterior chamber and the anterior chamber.
When the lens is turbid to such a serious extent as to cause blindness, it is replaced with an artificial lens to recover the sight. In this regard, surgical insertion of an artificial lens in the eyeball is well known. For example, the anterior chamber angle, the ciliary body, or the capsular lentis is the place where an artificial lens is inserted. In addition, an artificial lens may be supported on the iris 3.
However, some of these tissues, e.g. the iris, are anatomically so unstable that an artificial lens cannot be fixed thereto. For example, if an artificial lens is surgically transplanted to be supported by the iris, the patient may suffer from a complication. In addition, because the conventional sites in which an artificial lens is inserted are distant from the cornea, in which the greatest refraction of incident beams occurs, the actual refraction after the operation often does not agree with expected refraction.
In the past, various U.S. patents have issued relating to such intraocular lenses. For example, U.S. Pat. No. 4,950,288, issued on Aug. 21, 1990 to C. D. Kelman, describes a corrective intraocular lens which is inserted through an incision into the eye and implanted therein in spaced relationship to the natural lens. This intraocular lens includes a lens body having a pair of opposed haptics including a first insertable leading haptic and a last insertable trailing haptic. Each haptic outwardly terminates in a transverse edge having a pair of laterally spaced-apart and outwardly projecting contact lobes for engaging an adjacent eye tissue portion at a corresponding pair of spaced-apart tissue points. Unfortunately, this type of intraocular lens rotates relatively easily in the anterior chamber. Continued use of this type of intraocular lens can cause chronic uveitis, glaucoma, iris deformity and intraocular hemorrhage. This intraocular lens is only composed of the optical lens and the haptics. The haptics are positioned at the anterior chamber angle in order to stabilize the intraocular lens. But the angle and the iris near the angle are not as rigid and stable as the cornea or sclera for the fixation of an intraocular lens. The iris plane is like a curtain and can fluctuate easily. As a result, fixation of the intraocular lens in this area is quite difficult. Additionally, it is very difficult to measure the actual interangular diameter of the anterior chamber (the diameter from the anterior chamber angle at one point to the one at the opposite side) accurately. As such, it is very difficult to choose the proper diameter of the intraocular lens. If a smaller intraocular lens is chosen, then it may create a very loose intraocular lens fitting which can cause continuous rotation in the anterior chamber so as to result in chronic irritation of the intraocular structure. If a larger intraocular lens is chosen, the intraocular lens would push the iris near the angle so as to result in iris and pupil deformities.
U.S. Pat. No. 6,322,589, issued on Nov. 27, 2001 to J. S. Cumming, teaches an intraocular lens having fixated haptics. This intraocular lens is implanted within the natural capsular bags of human eyes. These lenses have features on the distal end portions so as to prevent movement or sliding thereof relative to fibrosis pockets or tunnels defined about proximally adjacent haptics portions in order to fixate the haptics against dislocation. Unfortunately, this type of intraocular lens will have the tendency to move or rotate in the capsular bag until capsular fibrosis develops. This intraocular lens is not supported, in any way, by the cornea or the sclera but is solely supported by the capsular bag.
It is an object of the present invention to overcome the above-stated problems encountered in the prior art and to provide an artificial intraocular lens that can be supported by the cornea.
It is another object of the present invention to provide an artificial intraocular lens which displays a desirable refraction index, can be firmly fixed to the cornea with few complications after surgical transplantation, and also allows the liquid of the anterior chamber to flow smoothly so as to prevent the endothelial cells of the cornea from being damaged.
It is a further object of the present invention to provide a fixation technique for such an intraocular lens which fixes the intraocular lens within the anterior chamber so as to decrease the likelihood of irritation of the iris, cataracts, glaucoma, chronic uveitis, hemorrhages, or distortion of the shape of the pupil.
It is another object of the present invention to provide a method and apparatus for installing an intraocular lens which allows the intraocular lens to be easily manipulated for angle adjustment, replacement, or refractive power accuracy.
It is another object of the present invention to provide a method and apparatus for installing an intraocular lens which provides for astigmatism correction.
It is another object of the present invention to provide a method and apparatus for securing an intraocular lens within the anterior chamber which facilitates the free convection of aqueous humor against the corneal endothelium so as to minimize potential damage thereto.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.